The invention relates to an apparatus for removing substances from the surface of a liquid, particularly the oil floating on the cooling lubricant of a machine tool, with a receiving disk connected to a rotary drive and intended for partial immersion in the liquid, a device for removing the substance received from the receiving disk and with transfer means for draining off to the outside the removed substance over the wall of the liquid-enclosing container.
For removing the oil from the surface of a liquid, a known apparatus of this type has a plastic disk driven by an electric motor and provided with a smooth surface to which the oil is attached by adhesion, so as to be subsequently removable by a stripper fixed to the apparatus and then flows away via a channel extending over the container edge. The actual apparatus is screwed firmly to the liquid container. As the oil must flow of its own accord over the surface of the liquid to said apparatus, it functions relatively slowly and only makes it possible to reduce the thickness of the oil layer on the liquid without completely removing it, because as from a certain minimum thickness the oil layer breaks and consequently no longer flows towards the apparatus. The remaining oil layer prevents the air supply to the liquid, as is e.g. particularly advantageous for the cooling lubricants of machine tools due to the premature aging which then occurs.